The present invention relates to a new and improved bobbin exchange apparatus on a ring spinning or ring twisting machine.
Generally speaking, the bobbin exchange apparatus of the present invention is of the type comprising a transporting belt which is provided with a plurality of bobbin holders for taking-up or receiving bobbin tubes. The mutual distance or spacing of the bobbin holders is equal to the spindle gauge, and the transporting belt extends substantially horizontally in the longitudinal direction of the machine.
On ring spinning and ring twisting machines spun yarns or twisted threads, respectively, are simultaneously wound onto a plurality of bobbin tubes placed onto spindles using a ring and traveller system. After the bobbin packages have been wound to completion, they are exchanged for empty bobin tubes. On a machine this bobbin exchange operation is simultaneously effected for all bobbin tubes. According to Austrian Patent No. 271,278 and the corresponding U.S. Pat. No. 3,370,411 a doffer beam is provided for this purpose. Such beam is equipped with a gripper for each of the bobbin tubes to be exchanged. By performing appropriate movements of the doffer beam along the columns which support it, and by suitably pivoting the latter, the full bobbin packages are transferred onto a transporting belt from which empty bobbin tubes are removed and are then donned onto the spindles.
This type of bobbin tube exchange is associated with the disadvantage that on the machine a relatively large amount of space is required between the spindle bearings or bolsters and the transporting belt. As a result, the spindle bolsters cannot be designed with the length required. And on the other hand, the spindle rails have to be designed to possess reduced dimensions which, in turn, impairs their stability.
According to a bobbin exchange device as is known from Swiss Patent No. 611,351, the transporting belt which is simultaneously pivoted with the doffer beam, which is used for exchanging the bobbin tubes, is pivoted through the same angle. Thus, no vertical movements of the doffer beam towards the transporting belt and away from it are required for taking-up or receiving the empty tubes and for placing the full bobbin package tubes. The bobbin exchange can be accomplished with a movement forming an acute angle with respect to the vertical direction. Thus, a certain saving in space is realized in comparison to the first-mentioned bobbin exchange device, since here the doffer beam no longer is required to be moved in the space available between the bobbin tubes placed on the transporting belt and the spindle bearing housings. However, also according to this second mentioned patent, the spinning machine cannot be equipped with a profile of the spindle rail which provides great stability, nor can optimum space utilization or good spinning geometry be attained.
The above-mentioned disadvantages are avoided on machines with such bobbin exchange devices known in practice in advantageous manner, when the transporting belt is arranged, with respect to the machine, so as to be inclined towards the front. It has been found, however, that due to the inclined position of the transporting belt the situation can arise that the bobbin tubes which are retained on the transporting belt by the bobbin holders are not exactly held in the intended position.
It may particularly occur that the empty bobbin tubes, as concerns their inclined position, are not all inclined at exactly the same angle of inclination. Under these circumstances there is not ensured for a correct bobbin tube exchange operation. At this point it should be noted as concerns the discussed state of the art, particularly the device known from the abovementioned Swiss patent, due to the repeated pivoting or tilting of the transporting belt together with the doffer beam including the bobbin tubes placed on the transporting belt, this disadvantage also exists in this prior art equipment.